Re: FOR EXPERTS: Template Class: Type Constraints [modified] - C# Discussion Boards

Re: Timed resize of image

6-Feb-09 3:53

with a paintEvent method, the timer should set a global scale value, and then call the panel.Invalidate() method

the paint event should, draw the required image using the global scale value and other positioning calculations

My opinion is... If someone has already posted an answer, dont post the SAME answer

m.otte6-Feb-09 5:31

m.otte

6-Feb-09 5:31

Mmm, I see. Interesting. Will try it and am curious what it will do to the timing?

Thanks

Re: Timed resize of image [modified]

Luc Pattyn6-Feb-09 6:47

Luc Pattyn

6-Feb-09 6:47

Right. If you want specific actions with images, don't rely on PictureBoxes; use some drawing surface and paint the stuff yourself. Panels are ideal for such purposes.

Smile | :)

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modified on Friday, February 6, 2009 12:57 PM

modified on Friday, June 10, 2011 11:30 AM

Re: Timed resize of image

musefan6-Feb-09 6:49

Re: Timed resize of image [modified]

6-Feb-09 6:49

Thanks for the backup Big Grin | :-D

My opinion is... If someone has already posted an answer, dont post the SAME answer

Luc Pattyn6-Feb-09 6:45

Luc Pattyn

6-Feb-09 6:45

Hi,

almost all asynchronous devices including serial ports, timers, etc. use extra threads. All timers except one (Forms.Timer) tick on a separate thread, and are not suited for directly touching any Control. One either needs Control.InvokeRequired + Control.Invoke, or use Forms.Timer

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

modified on Friday, June 10, 2011 11:31 AM

FOR EXPERTS: Template Class: Type Constraints

Axonn Echysttas6-Feb-09 2:12

Axonn Echysttas

6-Feb-09 2:12

Hey everybody... I got a question for advanced C# programmers. I've been playing around with type constraints for template classes, and I got stuck.
I used [ and ] instead of < and > for template classes because I wanted to have HTML code for you to see better what code I got.

In the C# 3.0 specification (and I will quote directly from Microsoft's document), it's said that this will work:

class B[T] where T: IEnumerable {...}
class D[T]: B[T] where T: IEnumerable {...}
class E[T]: B[List[T]] {...}

Because (so they say):

"Since type parameters are not inherited, constraints are never inherited either. In the example below, D needs to specify the constraint on its type parameter T so that T satisfies the constraint imposed by the base class B[T]. In contrast, class E need not specify a constraint, because List[T] implements IEnumerable for any T."

Now... I put this pre into VS 2008 and the compiler won't work. My pre:

class B[T] where T : IEnumerable[T] { }
class D[T] : B[T] where T : IEnumerable[T] { }
class E[T] : B[List[T]] { }

Error:

"Error 1 The type 'System.Collections.Generic.List[T]' cannot be used as type parameter 'T' in the generic type or method 'FunFollAdmin.frmMain.B[T]'. There is no implicit reference conversion from 'System.Collections.Generic.List[T]' to 'System.Collections.Generic.IEnumerable[System.Collections.Generic.List[T]]'. D:\Order\A1.FunFoll Administrator [FFA]\2009-01-25\FunFollAdmin\frmMain.cs 46 10 FunFollAdmin"

Even more......... not even this works:

B[test] test = new B[test]();

Error:

"Error 1 The type 'FunFollAdmin.frmMain.test' cannot be used as type parameter 'T' in the generic type or method 'FunFollAdmin.frmMain.B[T]'. There is no implicit reference conversion from 'FunFollAdmin.frmMain.test' to 'System.Collections.Generic.IEnumerable[FunFollAdmin.frmMain.test]'. D:\Order\A1.FunFoll Administrator [FFA]\2009-01-25\FunFollAdmin\frmMain.cs 216 9 FunFollAdmin
Error 2 The type 'FunFollAdmin.frmMain.test' cannot be used as type parameter 'T' in the generic type or method 'FunFollAdmin.frmMain.B[T]'. There is no implicit reference conversion from 'FunFollAdmin.frmMain.test' to 'System.Collections.Generic.IEnumerable[FunFollAdmin.frmMain.test]'. D:\Order\A1.FunFoll Administrator [FFA]\2009-01-25\FunFollAdmin\frmMain.cs 216 28 FunFollAdmin"

Even though I have implemented the class test correctly:

class test : IEnumerable[int]
{
  public test () { }
  #region IEnumerable[int] Members

  public IEnumerator[int] GetEnumerator ()
  {
    throw new NotImplementedException();
  }

  #endregion

  #region IEnumerable Members

  System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator ()
  {
    throw new NotImplementedException();
  }

  #endregion
}

-= E C H Y S T T A S =-
The Greater Mind Balance

Blending C++ with COM ^

Have a break on my website! Spread the word? Please?

Re: FOR EXPERTS: Template Class: Type Constraints [modified]

Mirko19806-Feb-09 2:57

Mirko1980

6-Feb-09 2:57

The compiler is right. You wrote where T : IEnumerable[T]: this means that T must be an enumeration of itself!
Note that the MSDN sample uses the non-generic version of IEnumerable (where T : IEnumerable), meaning that T can be any enumeration.

modified on Friday, February 6, 2009 10:10 AM

Axonn Echysttas6-Feb-09 3:40

Axonn Echysttas

6-Feb-09 3:40

Note that the MSDN sample uses the non-generic version of IEnumerable (where T : IEnumerable[T]), meaning that T can be any enumeration.

You mean where T : IEnumerable

Ok but how do you declare it so? Because if I declare it so, it says

Error	1	Using the generic type 'System.Collections.Generic.IEnumerable<t>' requires '1' type arguments	D:\Order\A1.FunFoll Administrator [FFA]\2009-01-25\FunFollAdmin\frmMain.cs	48	33	FunFollAdmin</t>

I used the code directly from MSDN

 interface IMyInterface<br />
    {<br />
    }<br />
<br />
    class Dictionary[TKey, TVal]<br />
      where TKey : IComparable, IEnumerable<br />
      where TVal : IMyInterface<br />
    {<br />
      public void Add (TKey key, TVal val)<br />
      {<br />
      }<br />
    }

Same error as above!!! I don't get it! Oh boy......... ::- (

Error	1	Using the generic type 'System.Collections.Generic.IEnumerable<t>' requires '1' type arguments	D:\Order\A1.FunFoll Administrator [FFA]\2009-01-25\FunFollAdmin\frmMain.cs	48	33	FunFollAdmin</t>

-= E C H Y S T T A S =-
The Greater Mind Balance

Blending C++ with COM ^

Have a break on my website! Spread the word? Please?

Mirko19806-Feb-09 4:26

Mirko1980

6-Feb-09 4:26

You mean <code>where T : IEnumerable</code>

Yes, I mistyped. Corrected now.

You must add using System.Collections in order to use the non-generic version of IEnumerable (or you use its full name: where T : System.Collections.IEnumerable).

Axonn Echysttas6-Feb-09 5:19

Axonn Echysttas

6-Feb-09 5:19

Ah, damn. I had using System.Collections.Generic; but not using System.Collections;

Thank you Mirko! ::- )

That fixed it.

-= E C H Y S T T A S =-
The Greater Mind Balance

Blending C++ with COM ^

Have a break on my website! Spread the word? Please?

Mirko19806-Feb-09 5:24

Mirko1980

6-Feb-09 5:24

You welcome Smile | :)

concateing strings in c#

lawrenceinba6-Feb-09 1:32

6-Feb-09 1:32

hi friends

i want to implement a logic .. string input will be given...it should merge only single characters..pls help

eg.. behind r m d street

o/p expected is behind rmd street

any body help me out with apt logic......

the quieter u become more u hear

musefan6-Feb-09 1:38

6-Feb-09 1:38

how bout a function along the lines of the following

string MergeFunction(string value)
{
result = value;

for(int i = 0; i < value.length; i++)
{

if(value[i-1] == ' ' && value[i+1] == ' ')//single char
{
result = result.remove(i+1, 1);
}

}

return result;
}

dont forget you also need to include some check for handling if i == 0; or i == value.length -1;
because it will throw a index out of bounds error as it is.

EDIT: oops you will need some sort of count for the number of spaces currently remove so you can subtract it from the value when using result.remove

result.remove(i+1-count, 1);

My opinion is... If someone has already posted an answer, dont post the SAME answer

lawrenceinba6-Feb-09 2:57

6-Feb-09 2:57

can u give me the entire code with my given input.... pls...

it shows out of bound error even i do as u said...

pls help me out

the quieter u become more u hear

musefan6-Feb-09 3:15

6-Feb-09 3:15

Ok as its not too much code, though im not testing so let me know any errors

///<summary>
///Merges any characters on there own
///<summary>
///<param name="s">The string to parse</param>
string MergeFunction(string s)
{
string result = s;
int count 0;//used to count num of removed chars, this is because length of result may get shorter 
            //than the length of s due to removal of spaces
for(int i = 0; i < s.Length-1; i++)//no need to test last char so use s.length -1 
{
   if(i == 0)//if first char
   {
        if(s[i+1] == ' ')//check if next char is a space
        {
            result = result.Remove(i+1-count, 1);
            count++;
        }
   }
   else//any char other than the first and last(due to for loop limit)
   {
       if(s[i-1] == ' ' && s[i+1] == ' ')//check if both sides of char is a space
        {
            result = result.Remove(i+1-count, 1);
            count++;
        }

   }

}

return result;
}

My opinion is... If someone has already posted an answer, dont post the SAME answer

lawrenceinba6-Feb-09 5:51

6-Feb-09 5:51

using System;
using System.Collections;

class chapter10 
{
static void Main() 

///<summary>
///Merges any characters on there own
///<summary>
///<param name="s">The string to parse</param>
//string MergeFunction(string s)
{
string result = "s y t y i";
int count= 0;//used to count num of removed chars, this is because length of result may get shorter 
            //than the length of s due to removal of spaces
for(int i = 0; i < result.Length-1; i++)//no need to test last char so use s.length -1 
{
   if(i == 0)//if first char
   {
       if (result[i + 1] == ' ')//check if next char is a space
        {
            result = result.Remove(i+1-count, 1);
            count++;
        }
   }
   else//any char other than the first and last(due to for loop limit)
   {
       if (result[i - 1] == ' ' && result[i + 1] == ' ')//check if both sides of char is a space
        {
            result = result.Remove(i+1-count, 1);
            count++;
        }

   }

}

//return result;

Console.WriteLine( result);
}
}</summary></summary>

this is my modified code.... but it checks only first and second char....wat should i do now.... pls specify changes alone in bold letter...
thanks u very much for ur help

the quieter u become more u hear

musefan6-Feb-09 6:02

6-Feb-09 6:02

lawrenceinba wrote:
string result = "s y t y i";

Should be :-

string s = "s y t y i";//you need an original instance, not just the result instance
string result = s;

lawrenceinba wrote:
if (result[i + 1] == ' ')//check if next char is a space

Should be :- s[i + 1] == ' '

lawrenceinba wrote:
if (result[i - 1] == ' ' && result[i + 1] == ' ')//

Should be :- s[i - 1] == ' ' && s[i + 1] == ' '

but please make it a seperate function and call it from within your main, its much better practise i.e.

string result = MergeFunction("s y t y i");

My opinion is... If someone has already posted an answer, dont post the SAME answer

Guffa6-Feb-09 5:54

Guffa

6-Feb-09 5:54

There's a one-liner for everyting. Wink | ;)

text = Regex.Replace(text, @"\b([^ ]) (?=[^ ]\b)", "$1");

Despite everything, the person most likely to be fooling you next is yourself.

lawrenceinba6-Feb-09 6:35

6-Feb-09 6:35

input= " s y t b/d y i yt"

according to ur code it give out sytb/d yi yt

only single characters should be joined what should i do now

if it has any delimiters it should not be joined... delimiters are (!#&*;/)

thanks

the quieter u become more u hear

Guffa6-Feb-09 6:50

Guffa

6-Feb-09 6:50

Use a positive lookbehind to match a space of the beginning of the string followed by a non-space character, and look for a space or the end of the string instead of the word boundary in the lookahead.

Despite everything, the person most likely to be fooling you next is yourself.

lawrenceinba6-Feb-09 7:02

6-Feb-09 7:02

ya tat's wat im expecting but how to i do it using regex

for tat i should use for loop.. isn't it..

is there any way in regex

the quieter u become more u hear

Guffa6-Feb-09 9:00

Guffa

6-Feb-09 9:00

lawrenceinba wrote:
ya tat's wat im expecting

wy ar yu takin lik dis?

lawrenceinba wrote:
but how to i do it using regex

for tat i should use for loop.. isn't it..

is there any way in regex

Yes, there is. If you do what I already explained, it looks like this:

text = Regex.Replace(text, @"(?<=^| )([^ ]) (?=[^ ](?: |$))", "$1");

Despite everything, the person most likely to be fooling you next is yourself.

lawrenceinba6-Feb-09 9:05

6-Feb-09 9:05

oops......i'm very sorry... i thought you could understand.....here after i'll type fully...

thanks

the quieter u become more u hear

lawrenceinba6-Feb-09 9:12